Industrial impact on sustainable dairy farms: Essential elements, hazardous metals and polycyclic aromatic hydrocarbons in forage and cow's milk

Sergio Forcada; Mario Menéndez Miranda; François Stevens; Luis J Royo; Juan Antonio Fernández Pierna; Vincent Baeten; Ana Soldado

doi:10.1016/j.heliyon.2023.e20977

Industrial impact on sustainable dairy farms: Essential elements, hazardous metals and polycyclic aromatic hydrocarbons in forage and cow's milk

Heliyon. 2023 Oct 16;9(10):e20977. doi: 10.1016/j.heliyon.2023.e20977. eCollection 2023 Oct.

Authors

Sergio Forcada¹, Mario Menéndez Miranda¹, François Stevens², Luis J Royo¹, Juan Antonio Fernández Pierna², Vincent Baeten², Ana Soldado³

Affiliations

¹ Regional Service for Agrofood Research and Development (SERIDA), PO Box 13, 33300, Asturias, Spain.
² Department of Knowledge and Valorization of Agricultural Products, Walloon Agricultural Research Centre (CRA-W), Chaussée de Namur 24, 5030, Gembloux, Belgium.
³ Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Avda. Julián Clavería 8, 33006, Asturias, Spain.

Abstract

Sustainable dairy farms are characterised by the self-production of forage for animal feed. These farms are sometimes located near industrial areas, entailing a risk of food chain contamination with hazardous metals and polycyclic aromatic hydrocarbons (PAHs). Accordingly, evaluating the impact of pollution on forage and milk is of great interest. In this study, the effects of industrial factors on sustainable forage from 43 dairy farms and possible correlations between inorganic elements and PAHs were studied. Spearman's correlation and principal component analysis (PCA) were performed for the forage and milk. Most of the inorganic elements in the forage were below the maximum residual limits for cadmium (Cd) and lead (Pb), established in EU 2013/1275 and EU 2019/1869, respectively. However, arsenic (As) and mercury (Hg) levels were above their respective limits in the forage (EU 2019/1869). No milk samples exceeded the maximum residual limits for Pb (EU 488/2014) or Cd (EU 1881/2006) in dairy products. Heavy-weight PAHs (HW-PAHs, four or more aromatic rings) were detected in forage but not in milk. In the forage samples, HW-PAHs were positively correlated with Zn and Cd. In addition, some hazardous metals (chromium (Cr), iron (Fe), As, Hg, and Pb) also were positively correlated with Zn and Cd. Interestingly, no correlations were found between forage pollutants and milk, suggesting that these pollutants have a low transfer rate to milk. The PCA results highlighted the predominant contribution of PAHs to the global variance in forage samples collected at different distances from industrial areas. In milk, the contributions of hazardous metals and PAHs were more balanced than in forages. Finally, when distances to potential pollution sources were included in the PCA of forage samples, a negative correlation was observed between the former and the concentrations of HW-PAHs, Cd, and Zn, suggesting that thermal power plants and steel factory emissions were the main sources of polluting forage in this area.

Keywords: Dairy farms; Forage; Heavy metals; Milk; Polycyclic aromatic hydrocarbons.